Portable heaters have been in existence for a long time and have been the subject of much development effort. Examples of this type of portable heater is disclosed in U.S. Pat. Nos. 4,081,238 and 4,089,642. Because of the dangerous nature of such heaters, certain standards have been established by Underwriter Laboratories (UL). One such standard involves the fuel line assembly which is connected between the fuel tank and the fuel discharge nozzle which discharges fuel into the combustion chamber for ignition by an ignition element such as a spark plug. In order to meet UL approval, the standard for the fuel line assembly requires a rigid metal tube connection between the fuel discharge nozzle assembly and the tank. Although meeting this standard is required to mark the space heater as having met UL approval, an addendum standard permits flexible hoses such as rubber or other synthetic material for transferring the fuel from the fuel tank to the nozzle of the burner. UL will not certify portable heaters that utilize a flexible hose. The flexible hose presents the problem of connecting the flexible hose securely to the tank and the nozzle assembly. Flexible rubber or synthetic rubber hose is subject to rot and deterioration. This problem is critical in that if the rubber hose is severed (cut) or broken between the tank and the fuel discharge nozzle assembly, fuel spills will result and catch on fire.
One challenging problem in utilizing a rigid metal tube such as steel, copper, or aluminum, is the dilemma of how to connect the rigid metal tube to the tank and to the fuel filter and particularly at the same time provide access to service the fuel filter within the tank. This problem has resulted in the present day manufacturers of portable space heaters of the type as disclosed in U.S. Pat. Nos. 4,081,238 and 4,089,642 utilizing flexible hose and therefore the present day units cannot be certified as meeting UL approval and cannot be marked as such since they have only been tested to the addendum standard. To date, the reason for using the flexible hose is that those skilled in the art have not been able to conceive of any way to connect a rigid metal tube to the tank so that it is sufficiently secure and to eliminate the possibility of the rigid tube being disconnected from the tank by reason of movement, jarring, etc., of the portable heater. Apparently, the manufacturers of such portable heaters have relied upon the flexible hose to absorb any such jarring movements. This is dangerous in the fact that flexible hose can be jarred loose which could result in a fire.
Another challenging problem in the type of portable heaters as above described is the cost of production of such heaters. Therefore, there is a constant effort to modify the various components of the heater. The present invention preferably utilizes a plastic tank and a unique connection to it of a rigid metal tube.